One person was found by police rescuers shortly after the accident and taken to Syosset Hospital in critical condition. Marine Patrol and Nassau continued the search and at about 3 a.m. found two others still in the submerged yacht. They were all taken to an area hospital Lack would not identify.

Preliminarily, Lack said police believe the boat capsized from the wake of other boats, an account supported by eyewitnesses from another boat that picked up many of those thrown from the yacht into the waters.

The others in the boat were saved by private vessels and emergency agencies were taken to Seawanhaka Corinthian Yacht Club on Centre Island and six more to Theodore Roosevelt Memorial Park in Oyster Bay, police said.

Lack said most of those rescued were taken to hospitals for observation. He did not think any of the injuries were serious.

One nearby boater said he saw the Silverton yacht turn right, then tip over after it was hit by a wake.

"It was like in slow motion," Sammy Galasso of Oyster Bay recounted in a phone interview. "All of a sudden, a lot of bodies were in the water."

Lack would not comment on whether children were among the missing or deceased.

At the yacht club, one man, who did not identify himself, said his brother, the boat's owner, was very experienced on the waters and other experienced boaters were on board with their family. He said the boat was not overloaded.

"It's a big boat," he said, adding that the weather was not a factor. He said all of the people on board ended up in the water.

Frankie Barbone, 15, of Bayview, who is Galasso's nephew, said the waves almost came up over the speedboat.

After the yacht capsized, the teenager said, he saw one person holding onto a chair in the water. His family pulled people out of the water onto the speedboat, Frankie said, but no one had on life vests.

Two others taken to Glen Cove Hospital were in stable condition, she said.

Dozens of police and rescue vehicles, along with at least one helicopter were involved in the search. They gathered at Theodore Roosevelt Memorial Park in Oyster Bay and the yacht club into Thursday morning.

Due to fireworks all over the area, roads and waterways were clogged with departing cars and boaters, hampering rescue efforts, in addition to a squall with heavy rain that came through the Bayville area around 10 p.m.

This story has been changed to correct the spelling of Sammy Galasso's name.